Q: Airport utility not recognizing airport express extender

Was told I could extend my wi-fi with a second Airport Express

Not sure what you were told, but the AirPort Express can only "extend" the network wirelessly if you have another Apple router providing the network that will be extended. Another way to say the same thing is that if you want to extend the network wirelessly with an Apple router, you will need at least two of them.

Apple will only allow you to wirelessly extend the network one time, not two.  In other words, if you already have one AirPort Express set up to wirelessly extend the network, you cannot extend again with another Express that connects to the Express that is already extending.

Now, if you are asking if two AirPort Express devices can both extend an Apple network, the answer would be yes.  But in order for this to work, both Express devices must connect directly to the main Apple router, so they would need to be about the same distance from the "main" AirPort router......AND.....both Expresses would need to be closer to the main AirPort than they are to each other.

For example, say you had an AirPort acting as the "main" router for the network, and it was located in the middle of your rectangular shaped home.  You could have one Express on the "left" side of the house to extend the signal that way and another Express on the "right" side of the house to extend the network that way.  Both Expresses connect directly to the main router in this type of setup.

And did I read it only extends for Apple products?

Yes you did. It's right there in the product literature. If you want an Express to "extend" the signal, you must have another Apple router providing the network that will be extended.

Extend an existing Wi‑Fi network’s range.

If you already have a wireless network in your home and want to extend its range, AirPort Express can help. Just place it in range of your primary base station — an AirPort Extreme, AirPort Time Capsule, or another AirPort Express

http://www.apple.com/airport-express/

So, if you could clarify things a bit by telling whether you have a "main" Apple router than provides your network, and explain a bit more about what you want to accomplish, we might be able to help.

So, the AirPort Express that is working now has now is the current second generation model.....with both a WAN and LAN port?

And, you want to extend the signal of your "main" AirPort Express with a another second generation model?

Are you still using OS X (10.5.6) on your Mac, as your profile indicates?  If not, what operating system is currently installed? If you are not sure, click the Apple icon in the upper left corner of the screen, then click About This Mac and report back on the OS X Version number that you see there.

Thanks for the info. Please follow these instructions carefully.

Temporarily, move the newest AirPort Express that has not yet been installed to the same room or close proximity to your "main" AirPort Express.

Power up the newest Express for a full minute. Then, hold in the reset button on the back of the Express for 7 to 8 seconds and then release. Allow a full minute for the Express to restart to a slow, blinking amber light status

Power off both the "main" AirPort Express and newest Express

Wait a minute

Then, power up the "main" AirPort Express and let it run a full minute

Now power up the newest Express and let it run a full minute

On your Mac running 10.7.5.......

Click the WiFi menu icon at the top of the screen

Look for a listing of New AirPort Base Station

Click on AirPort Express

When you click on AirPort Express, that will start up the setup "wizard". It will take a few seconds to analyze the network and then display a screen that looks like this, except that you will see your devices pictured and the name of your wireless network.

Type in a name that you want to call the newest Express

Click Next

The setup wizard will set everything up for you automatically in the next screen that appears

After a minute or so, you will see a message of Setup Complete

Click Done and close the wizard window

Now move the Express that you just set up to a location that is about half way between the "main" Express and the general area where you need more wireless signal coverage.  The more that you have line-of-sight between the two AirPort Express devices, the better the network will operate.

Power up the Express and you should be all set.

Restart your Mac to see if AirPort Express appears, if yes then proceed

If no,

Try on another Mac, or an iPhone or iPad.

On the iPhone or iPad.....

Go to the Home screen

Tap Settings

Tap WiFI

Look for Set Up New Base Station

Tap on AirPort Express

If the Express still does not appear. perform the Hard Reset again on the Express by holding the reset button for 7-8 seconds and then release.

If still no luck, you have a defective Express

Installing a new AirPort is normally as simple as.....

Powering up the device

Selecting it in WiFi menu

Entering a device name

Clicking Next

Not sure what else could possibly go wrong.

Try the setup with an iPhone or iPad.

If that fails, or you see the "unexpected" error again, then I think you have a defective Express.

Link Local Only should have already been selected by default.......unless you were provided instructions by your ISP to set up IPv6 in a specific way and you changed the settings.

As this point though, anything is possible.